Methods to improve the data carrying capacity of CATV DOCSIS systems and other communications systems are disclosed. Communications channels may be more efficiently spaced with reduced or absent guard bands by using receivers with adaptive signal cancellation methods, equalizing circuits, or polyphase filter banks and Fast Fourier Transform signal processing methods to correct for higher levels of cross-talk. QAM type communications channels may also be utilized on a synchronized two-transmitter at a time basis by adjusting the transmitters to predefined signal levels, such as +1, −1, +½, −½ to enable the combined signals to be distinguished at the receiver. These two methods may be combined to create a still higher data throughput system.

One embodiment is directed to a method comprising deciding to multiplex the data of at least two users within a super-constellation; determining the power split ratio among the at least two users; selecting a super-constellation; and based on the determined power split ratio, choosing a subset of the super-constellation points forming the superposition of modulation constellations of the at least two users.

A data transmission system includes a transmitter circuit. The transmitter circuit receives regular data bits and auxiliary data bits. The transmitter circuit encodes a first subset of the regular data bits to generate a first subset of encoded data comprising pairs of symbols that are used in quadrature amplitude modulation. The transmitter circuit encodes the auxiliary data bits and a second subset of the regular data bits to generate a second subset of the encoded data comprising at least one pair of symbols that are unused for encoding by the quadrature amplitude modulation. The transmitter circuit generates a modulated output signal that indicates the first and second subsets of the encoded data using pulse amplitude modulation.

An optical communication system that comprises a transmitter adapted to generate a signal by modulating a transmission data as low power consumption symbols of an amplitude modulation format and a monitoring data (MD) as high power consumption symbols of the amplitude modulation format, the MD comprising at least one transmitter parameter and/or at least one receiver parameter of communicating the transmission data. A binary logarithm of a total number of the low power consumption symbols and the high power consumption symbols is a non-integer.

A method of determining a modulation and coding scheme includes: acquiring UCI transmitted by UE, the UCI including at least a CQI index; determining whether the CQI index belongs to a CQI compression index representing at least two modulation and coding schemes; when the CQI index belongs to the CQI compression index, determining a modulation and coding scheme represented by the CQI compression index according to preset CQI compression index indication information; and determining modulation and coding configuration information for the UE according to the modulation and coding scheme, and transmitting the modulation and coding configuration information to the UE. By adopting the method of determining the modulation and coding scheme, a higher-order modulation and coding scheme may be configured for the UE based on a relevant CQI index to reduce calculation amount during analyzing the modulation and coding scheme.

An optical communication system that comprises a transmitter adapted to generate a signal by modulating a transmission data as low power consumption symbols of an amplitude modulation format and a monitoring data (MD) as high power consumption symbols of the amplitude modulation format, the MD comprising at least one transmitter parameter and/or at least one receiver parameter of communicating the transmission data. A binary logarithm of a total number of the low power consumption symbols and the high power consumption symbols is a non-integer.

A simple construction for a family of non-uniform APSK constellations by the radial isomorphism between squares to circles is provided. The mutual information values indicate gains of at least 0.5 dB up to 1.5 dB with respect to the state of the art, such as the DVB-S2X constellations with 256 symbols. The invention also provides for a low-complexity detector of high-order modulated signals.

A method of determining a modulation and coding scheme includes: acquiring UCI transmitted by UE, the UCI including at least a CQI index; determining whether the CQI index belongs to a CQI compression index representing at least two modulation and coding schemes; when the CQI index belongs to the CQI compression index, determining a modulation and coding scheme represented by the CQI compression index according to preset CQI compression index indication information; and determining modulation and coding configuration information for the UE according to the modulation and coding scheme, and transmitting the modulation and coding configuration information to the UE. By adopting the method of determining the modulation and coding scheme, a higher-order modulation and coding scheme may be configured for the UE based on a relevant CQI index to reduce calculation amount during analyzing the modulation and coding scheme.

Transmitting apparatus and receiving apparatus for communication systems using coded orthogonal frequency-division multiplexed (COFDM) dual-subcarrier modulation (DCM) signals. The same coded data is mapped both to COFDM subcarriers located in the lower-frequency half spectrum of the DCM signal and to COFDM subcarriers located in its upper-frequency half spectrum. The mapping of COFDM subcarriers in those half spectra employ labeling diversity preferred for reception of DCM with less error when accompanied by interfering additive white Gaussian noise (AWGN). In preferred forms of COFDM DCM signal, the quadrature amplitude modulation (QAM) of COFDM subcarriers is Gray mapped to position palindromic lattice-point labels along one of the diagonals of each square QAM constellation.

Systems and methods for orbital angular momentum (OAM)-based multidimensional wireless communication. The OAM-based multidimensional wireless communication is preformed with a transmitter for generating an RF modulated signal carrying a data sequence. Further included is an OAM antenna array including OAM antenna elements, each of which includes an azimuthal phase shifter and an antenna element. The azimuthal phase shifter shifts an azimuthal phase term of a wavefront generated by the antenna element such that the OAM antenna element imposes the multidimensional modulated signal on a pre-determined OAM mode of a carrier signal corresponding to the azimuthal phase term.